Load-bearing transducers bring safetyto Birmingham Symphony Hall.The imposing Birmingham Symphony Hall has aworld-wide reputation for its acoustic performance.Part of the acoustic control is a 35 tonne acoustichood situated directly above the stage.This hood, which is supported by 28 cable assemblies, can be raisedand lowered with servo assistance to vary the acoustics for a particularperformance.The hood is also used to mount additional lighting and audio equipment.Symphony Hall engineers were concerned about the increased loading tothe supporting cables. PCM was invited to design and supply a system which could monitor the loadscarried by the acoustic hood, with due attention being given to providing for alarge safety factor.After a detailed feasibility study, PCM proposed that a special strain gaugedload link transducer would be designed for in-line load monitoring of each of the28 supporting cables.These were designed and manufactured by PCMengineers using their experience in stress analysisand the precise application of strain gauges on thetransducers.The transducers were combined with speciallyconstructed electronic instrumentation, which performed both loadmeasurement and overload visual alarm functions.Each load transducer was constructed for precise load measurement whilstbeing required to fit within the existing cable assembly, with the minimum ofdisruption. PCM was also responsible for installation of the system whichrequired installing the load transducers in the cable line efficiently and withinstrict safety guidelines. With safety still in mind, procedures were established for protection of thetransducers and the associated electrical cables. This protection extendedfurther with the on-board electronic package for each transducer to ensurethat electrical interference did not effect output signals. Signal conditioning of each transducer provided a 4-10mA two-wire signaloutput. The resulting 28 individual transducer signals were routed to aninstrumentation console also situated on the acoustic hood. The instrumentation console provided digital readout of each load transducer,summation of all transducers to give total weight of the hood, and a presetalarm facility. Each alarm can be preset to a particular load value and ifexceeded will operate a LED display and a remote visual indicator.This ensures that when additional lighting or audio equipment is being installedon the hood, if the preset weight limit is exceeded, the LED display will alertengineers. PCM also devised a method to calibrate each load transducer and thecomplete system in-situ. This procedure ensured that all measurementsand alarms were precisely set to give optimum accuracy and performance. The entire installation was completed with minimal disruption and nowprovides a valued safety monitoring system.